feat: add new file

backend/app/database.py

@@ -0,0 +1,21 @@
+import os
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import declarative_base, sessionmaker
+
+
+DATABASE_URL = os.getenv(
+    "DATABASE_URL", "postgresql+psycopg://exam_user:exam_pass@localhost:5432/exam_helper"
+)
+
+engine = create_engine(DATABASE_URL, future=True, pool_pre_ping=True)
+SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False, future=True)
+Base = declarative_base()
+
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()